Apparatus and method of driving discharge tube lamp and liquid crystal display using the same

• US 8,421,739 B2
• Filed: 06/11/2002
• Issued: 04/16/2013
• Est. Priority Date: 02/09/2002
• Status: Expired due to Fees

• Current Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Original Assignee: LG Display Co., Ltd.
• Inventors: Chung, In Jae, Kim, Jong Dae
• Primary Examiner(s): Kumar, Srilakshmi K
• Application Number:
  US10/166,259
• Publication Number:
  US 20030151601A1
• Time in Patent Office: 3,962 Days
• Field of Search: 345/87, 345/102, 345690-693, 315/291, 315/307, 315/224
• US Class Current: 345/102
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: H05B 41/2824 using control circuits for the switching element H05B41/2822 takes precedence
• CPC Class Codes: H05B 41/3927 by pulse width modulation H05B41/3922 takes precedence
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A burst mode inverter that drives a discharge tube lamp in a manner that produces more emissions. A DC power supplier produces DC power. An inverter converts that DC power to AC power having a Pulse Width Modulated frequency that is between 2 and 3 times the system'"'"'s frame frequency. A duty cycle controller controls the duty-on-time of the Pulse Width Modulation frequency so as to be with the range of about 40% to 100%.

Claims

1. A driving apparatus having a discharge tube lamp, comprising:

a DC power supplier for producing DC power;

a burst mode inverter for converting the DC power to AC power, wherein the inverter responds to a Pulse Width Modulation frequency to modulate the DC power to produce the AC power, wherein the AC power is pulse width modulated; and

a controller for generating the Pulse Width Modulation frequency and adjusting a duty-on-time of the Pulse Width Modulation frequency in the range of about 40% to 99%,

wherein the controller multiplies a frame frequency to generate the Pulse Width Modulation frequency, and wherein the controller adjusts the duty-on time of the Pulse Width Modulation frequency to be within 40% and 99% of one period of the Pulse Width Modulation frequency.

2. The driving apparatus according to claim 1, further comprising at least one discharge tube for being driven by AC power supplied from the inverter.

3. The driving apparatus according to claim 1, wherein the controller receives the frame frequency and adjusts the Pulse Width Modulation frequency to be between 2 and 3 times the frame frequency.

4. The driving apparatus according to claim 1, wherein the duty-on-time of the Pulse Width Modulation frequency is 40% and the Pulse Width Modulation frequency is three times the frame frequency.

5. The driving apparatus according to claim 1, wherein the duty-on-time of the Pulse Width Modulation frequency is in the range of 50% to 99% and the Pulse Width Modulation frequency is twice the frame frequency.

14. The driving apparatus according to claim 1, wherein the adjusted Pulse Width Modulation frequency is about 2.5 times the frame frequency.

6. A driving method of a discharge tube lamp, comprising:

producing DC power;

generating a Pulse Width Modulation frequency and adjusting a duty-on-time of the Pulse Width Modulation frequency in the range of about 40% to 99%; and

utilizing the Pulse Width Modulation frequency to convert the DC power into AC power to be applied to the discharge tube lamp, wherein the AC power is pulse width modulated;

wherein generating the Pulse Width Modulation frequency includes multiplying a frame frequency to generate the Pulse Width Modulation frequency, and adjusting the duty-on time of the Pulse Width Modulation frequency to be within 40% and 99% of one period of the Pulse Width Modulation frequency.

7. The driving method according to claim 6, wherein adjusting the generated Pulse Width Modulation frequency includes adjusting the Pulse Width Modulation frequency to be 2 to 3 times the frame frequency in response to the signal.

8. The driving method according to claim 7, wherein the duty-on-time is in the range of 50% to 99% and the Pulse Width Modulation frequency is twice the frame frequency.

9. The driving method according to claim 7, wherein the duty-on-time of the Pulse Width Modulation frequency is 40% and the Pulse Width Modulation frequency is three times the frame frequency.

10. A liquid crystal display, comprising:

a liquid crystal display panel;

a DC power supplier for producing DC power;

a burst mode inverter for converting the DC power to AC power, wherein the inverter responds to a Pulse Width Modulation frequency to modulate the DC power to produce the AC power, wherein the AC power is pulse width modulated;

a controller for generating the Pulse Width Modulation frequency and adjusting a duty-on-time of the Pulse Width Modulation frequency in the range of about 40% to 99%; and

at least one discharge tube which turns on in accordance with the AC power supplied from the inverter to irradiate light to the liquid crystal display panel,

wherein the controller multiplies a frame frequency to generate the Pulse Width Modulation frequency, and wherein the controller adjusts the duty-on time of the Pulse Width Modulation frequency to be within 40% and 99% of one period of the Pulse Width Modulation frequency.

11. The liquid crystal display according to claim 10, wherein controller receives the signal having the frame frequency, and wherein the Pulse Width Modulation frequency is adjusted to be within the range of 2 to 3 times the frame frequency.

12. The liquid crystal display according to claim 10, wherein the duty-on-time of the Pulse Width Modulation frequency is 40% and the Pulse Width Modulation frequency is three times the frame frequency.

13. The liquid crystal display according to claim 10, wherein the duty-on-time of the Pulse Width Modulation frequency is in the range of 50% to 99% and the Pulse Width Modulation frequency is twice the frame frequency.